Article
Engineering, Electrical & Electronic
Chao Li, Yongjun Wang, Jingjing Wang, Haipeng Yao, Xinyu Liu, Ran Gao, Leijing Yang, Hui Xu, Qi Zhang, Pengjie Ma, Xiangjun Xin
Summary: In this paper, a novel convolutional neural network (CNN)-based perturbative nonlinearity compensation approach is proposed to overcome optical nonlinearity impairments. Experimental results in a coherent optical communication system show that the CNN equalizer can effectively reduce bit-error-ratio (BER) and improve performance.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Edson Porto da Silva, Metodi Plamenov Yankov
Summary: This paper investigates the performance of adaptive turbo equalization for nonlinearity compensation, proposing a scheme utilizing a recursive least-squares algorithm for adaptive channel estimation. By exchanging extrinsic information in every turbo iteration, the receiver is able to improve the performance of channel estimation and equalization, achieving lower bit-error-rate values. The proposed scheme allows for additional gains in signal-to-noise ratio and mutual information beyond what single-channel digital backpropagation can provide.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Takayuki Kobayashi, Junho Cho, Marco Lamponi, Guilhem De Valicourt, Christopher R. Doerr
Summary: The advancement of digital coherent technologies has increased system capacity per single-core single-mode fiber, approaching the Shannon limit, but extending optical bandwidth is necessary for increasing energy efficiency and reducing system complexity.
PROCEEDINGS OF THE IEEE
(2022)
Article
Engineering, Electrical & Electronic
Takeo Sasai, Etsushi Yamazaki, Yoshiaki Kisaka
Summary: This paper presents analytical results on different methods for estimating the longitudinal power profile in optical fibers at a coherent receiver. The two types of methods reviewed and analyzed are correlation-based methods (CMs) and minimum-mean-square-error-based methods (MMSEs). The paper provides analytical expressions for their output power profiles and spatial resolution, clarifying the theoretical performance limits and differences between the two methods. The study shows that the estimated power profiles of CMs are limited in spatial resolution and measurement accuracy, while MMSEs approach a true power profile under a fine spatial step size, canceling out the convolution effect.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Mehtab Singh, Moustafa H. H. Aly, Somia A. Abd El-Mottaleb
Summary: This paper proposes a combined wavelength division multiplexing (WDM)-polarization division multiplexing dual polarization (DP) in-phase quadrature modulation method in a hybrid single mode fiber (SMF)/free space optics (FSO) communication system for last mile connectivity. Four WDM channels carrying 112 Gbps data are used, along with 16-quadrature amplitude modulation signals. Digital signal processing algorithms are applied to compensate for SMF nonlinear losses, dispersion, and FSO channel losses. The simulation results demonstrate that the proposed SMF/FSO system can achieve transmission distances up to 50 km SMF + 3.5 km FSO under clear air conditions and down to 50 km SMF + 0.675 km FSO under heavy fog, with a total capacity of 448 Gbps at BER < 3.8 x 10(-3) and EVM% < 15%. Therefore, it is suggested to be used in the fifth generation last-mile wide-area networks.
OPTICAL AND QUANTUM ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Xiang Lin, Shenghang Luo, Sunish Kumar Orappanpara Soman, Octavia A. Dobre, Lutz Lampe, Deyuan Chang, Chuandong Li
Summary: This study proposes a machine learning-based scheme to mitigate the intra-channel optical fiber nonlinearity. The scheme utilizes perturbation treatment and a deep neural network to improve performance. Numerical simulations demonstrate the superiority of the proposed scheme over other methods.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Cenqin Jin, Nikita A. Shevchenko, Zhe Li, Sergei Popov, Yunfei Chen, Tianhua Xu
Summary: The paper investigates the impact of Equalization Enhanced Phase Noise (EEPN) on multi-channel optical communication systems, analyzes the nonlinear interaction between the signal and EEPN, and validates the analytical approach through numerical simulations and split-step Fourier simulations.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Hanzi Huang, Haoshuo Chen, Yetian Huang, Qianwu Zhang, Jian Chen, Nicolas K. Fontaine, Mikael Mazur, Roland Ryf, Yingxiong Song
Summary: This research investigates the beat interference caused by the spatial coupling between a pilot-tone and signals in self-homodyne coherent transmission. Conventional MIMO and UPIC-assisted MIMO are both affected by the beat interference and additional loss introduced by PT-signal crosstalk. Two novel MIMO processing schemes are proposed to handle the beat interference and show performance improvement in simulations and experiments.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Multidisciplinary Sciences
Jun Chen Ke, Xiangyu Chen, Wankai Tang, Ming Zheng Chen, Lei Zhang, Li Wang, Jun Yan Dai, Jin Yang, Jun Wei Zhang, Lijie Wu, Qiang Cheng, Shi Jin, Tie Jun Cui
Summary: A new-architecture space-frequency-polarization-division multiplexed wireless communication system is proposed using an anisotropic space-time-coding digital metasurface, which can improve the channel capacity and space utilization.
NATIONAL SCIENCE REVIEW
(2022)
Review
Optics
Svetlana Nikolaevna Khonina, Nikolay Lvovich Kazanskiy, Muhammad Ali Butt, Sergei Vladimirovich Karpeev
Summary: This review presents an attention-grabbing and up-to-date overview of major multiplexing techniques, including wavelength division multiplexing, polarization division multiplexing, space division multiplexing, mode division multiplexing, and orbital angular momentum multiplexing. It also discusses hybrid multiplexing methods and techniques. This unique review paper highlights the most prominent and recent progress in multiplexing techniques in one place.
OPTO-ELECTRONIC ADVANCES
(2022)
Article
Engineering, Electrical & Electronic
Benedikt Geiger, Eric Sillekens, Filipe Ferreira, Robert Killey, Lidia Galdino, Polina Bayvel
Summary: The performance of a wideband coherent receiver was studied, focusing on the impact of digital pre-distortion, geometric constellation shaping, pilot sequence detection, and the number of sub-channels in the super-channel. A net data rate of 2.36 Tb/s was achieved after transmitting an 8 x 26 GBd DP-GS-256-QAM super-channel over a distance of 75 km using a single 110 GHz electrical bandwidth receiver. The overall improvement in achievable information rate due to digital pre-distortion and tailored geometric constellation shaping was 1.2 bit/4D-sym.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Benshan Wang, Thomas Ferreira de Lima, Bhavin J. Shastri, Paul R. Prucnal, Chaoran Huang
Summary: Digital signal processing (DSP) has played a crucial role in optical communication systems, but the limitations of DSP chips have hindered the deployment of computationally costly algorithms. Photonic neural networks offer a promising solution to these challenges, with better performance and lower power consumption. This study proposes a photonic recurrent neural network (RNN) capable of processing optical signals and effectively addressing fiber nonlinearities in the photonic domain, achieving reduced power consumption and latency compared to traditional DSP chips.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Ryo Koma, Masamichi Fujiwara, Ryo Igarashi, Kazutaka Hara, Jun-Ichi Kani, Tomoaki Yoshida
Summary: This paper presents a new data-aided carrier frequency offset (CFO) estimation and compensation method for m-array phase shift keying (m-PSK) signals in burst-mode digital coherent reception. The key contributions of this method are the use of specially designed training symbols (TS) and a vector summation based feed-forward CFO estimation algorithm. Simulation and experimental results show that the proposed method has a wide CFO estimation range and high sensitivity detection for long-reach and high splitting ratio optical access.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Optics
Xiansong Fang, Xinyu Chen, Xiang Cai, Chuanchuan Yang, Fan Zhang
Summary: In this work, a novel architecture combining learned modified digital back-propagation (L-MDBP) and decision directed least mean square (DDLMS) adaptive equalizer is proposed to mitigate fiber nonlinearity in high-baud rate WDM systems. The proposed scheme achieves superior performance and lower computation complexity compared with conventional DBP by leveraging globally optimized model parameters and adaptive channel estimation. Furthermore, the adaptability of the architecture is enhanced using an online transfer learning (TL) technique with minimal initial training epochs.
Article
Engineering, Electrical & Electronic
Francisco Javier Garcia-Gomez, Gerhard Kramer
Summary: A nonlinear perturbation model is employed in this study to analyze the achievable rates of combined space-division multiplexing (SDM) and wavelength-division multiplexing (WDM) in fiber-optic channels. The analysis reveals that the power of nonlinear interference is at most quadratic in the number of SDM channels, while the achievable rates scale at least as the cubic root of the number of channels and linearly with the optimized launch power for large numbers of channels.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)